1. Field of the Invention
The present invention generally relates to a semiconductor device, and especially relates to a substrate processing apparatus and a substrate processing method used in manufacturing a super-miniaturized high-speed semiconductor device that includes a high dielectric film.
Recently, in ultra high-speed semiconductor devices, gate length of 0.1 micrometer or less has been realized with progress in miniaturized processing. Although the operation speed of semiconductor devices generally improves with miniaturization, film thickness of a gate insulation film of a miniaturized semiconductor is required to be decreased in correspondence to shortening of gate length by miniaturization according to a scaling rule.
2. Description of the Related Art
When the gate length is set to 0.1 micrometer or less, the thickness of a gate insulation film is required to be 1 or 2 nm, or even less, in the case that SiO2 is used. In the gate insulation film that is thin such as above, there is an inevitable problem that tunnel current increases, and, as the result, gate leak current increases.
For this reason, it has been proposed that a high dielectric material, such as Ta2O5, Al2O3, and ZrO2, HfO2, ZrSiO4 and HfSiO4, be applied to the gate insulation film, in which case, actual film thickness may become greater than the conventional film of SiO2. However, film thickness providing insulation equivalent to an SiO2 film is smaller, since the dielectric constant is higher than the SiO2 film. By using the high dielectric material such as above, a gate insulation film of about 2-5 nm thick can be used in an ultra high-speed semiconductor device where the gate length is 0.1 xcexcm or less, enabling the control of the gate leak current that arises from the tunnel effect.
When forming a high dielectric gate insulation film such as above on a Si substrate, the gate insulation film is required to be formed on a very thin SiO2 base oxidization film that is formed on the Si substrate in thickness less than 1 nm, typically less than 0.8 nm, in order to suppress spreading of a metallic element that constitutes the high dielectric gate insulation film in the Si substrate. In this case, the dielectric gate insulation film is required to be formed such that defects, such as boundary layer, may not be produced in the film. Further, when forming the high dielectric gate insulation film on the base oxidization film, it is desirable that the composition of the gate insulation film be such that the main component near the base oxidization film is SiO2, and the main component toward the upper surface of the high dielectric gate insulation film is the high dielectric material with gradual changes.
In order to form the high dielectric gate insulation film without defect, a plasma process in which charged particles are used cannot be employed. If the high dielectric gate insulation film is formed by the plasma CVD method, for example, a defect that acts as a trap of a hot carrier will be formed on the film as a result of plasma damage.
On the other hand, if the high dielectric gate insulation film is formed by the thermal CVD method, film thickness changes sharply due to the properties of the base insulation film used as the base, as has been found out by the inventor of the present invention. In other words, if the high dielectric gate insulation film is formed by the conventional CVD method, the film surface becomes irregular, and a gate electrode provided to the irregular surface of the gate insulation film causes degradation of the operating characteristics of the semiconductor device.
Accordingly, it is a general object of the present invention to provide a new and useful substrate processing method and processing apparatus that solve the problems described above.
A more specific object of the present invention is to provide a substrate processing apparatus and a substrate processing method for efficiently forming a high dielectric film on a substrate without a defect.
Another object of the present invention is to provide a substrate processing apparatus that includes:
a processing container,
a substrate holding stand prepared for holding a substrate-to-be-processed in the processing container,
a first processing gas supply unit that is provided to a first side of the substrate holding stand in the processing container, and supplies a first processing gas to the surface of the substrate-to-be-processed held on the substrate holding stand such that the first processing gas flows along the surface of the substrate-to-be-processed from the first side toward a second side that counters the first side,
a first exhaust opening provided to the second side of the substrate holding stand in the processing container,
a second processing gas supply unit that is provided to the second side of the substrate holding stand in the processing container, and supplies the second processing gas to the surface of the substrate-to-be-processed on the substrate holding stand such that the second processing gas flows from the second side toward the first side along the surface of the substrate-to-be-processed, and
a second exhaust opening provided to the first side of the substrate holding stand in the processing container.
Another object of the present invention is to provide a substrate processing method using a substrate processing apparatus equipped with a processing container that includes a substrate holding stand prepared in the processing container for holding the substrate-to-be-processed, a first processing gas supply unit provided to a first side of the substrate holding stand in the processing container, a first exhaust opening provided to a second side that counters the first side of the substrate holding stand in the processing container, a second processing gas supply unit provided to the second side of the substrate holding stand in the processing container, and a second exhaust opening provided to the first side of the substrate holding stand in the processing container, which includes
a step for performing a first process to the surface of the substrate-to-be-processed, wherein the first processing gas flows from the first processing gas supply unit on the first side toward the second side along the surface of the substrate-to-be-processed, and
a step for performing a second process to the surface of the substrate-to-be-processed, wherein the second processing gas flows from the second processing gas supply unit on the second side toward the first side along the surface of the substrate-to-be-processed, where,
in the process that performs the first process, discharging volume of the second exhaust opening is set smaller than discharging volume of the first exhaust opening, and,
in the process that performs the second process, the discharging volume of the first exhaust opening is set smaller than the discharging volume of the second exhaust opening.
Another object of the present invention is to provide a substrate processing apparatus that includes:
a processing container,
a substrate holding stand prepared for holding the substrate-to-be-processed in the processing container,
a processing gas supply unit that is provided to a first side of the substrate holding stand in the processing container, and supplies a processing gas to the surface of the substrate-to-be-processed on the substrate holding stand such that the processing gas flows from the first side toward a second side that counters the first side along the surface of the substrate-to-be-processed,
a first exhaust opening provided to the second side of the substrate holding stand in the processing container,
a radical source that is provided on the second side of the substrate holding stand in the processing container, and supplies radicals to the surface of the substrate-to-be-processed on the substrate holding stand such that the radicals flow from the second side toward the first side along the surface of the substrate-to-be-processed,
a second exhaust opening provided on the first side of the substrate holding stand in the processing container.
According to the present invention, a high dielectric film can be formed by laminating single-molecule layers on the substrate-to-be-processed by providing the first and second processing gas supply units on both sides of the substrate-to-be-processed in the processing container, countering each other, providing the first and second exhaust openings located on both sides of the substrate-to-be-processed, each opening countering with the first and second processing gas supply units, respectively, supplying the first processing gas supply unit, the first processing gas flowing along the surface of the substrate-to-be-processed, and being discharged from the first exhaust opening, and supplying the second processing gas or radicals from the second processing gas supply unit or the source of the radicals, respectively, the second processing gas or the radicals flowing along the surface of the substrate-to-be-processed, reacting with molecules of the first processing gas, which are previously absorbed by the surface of the substrate-to-to-processed, and being discharged from the second exhaust opening.
Other objects and features of the present invention will become clear from the detailed explanation about the preferred embodiments of the present invention described below.